PaginatedResponse<T>.fromJson constructor

PaginatedResponse<T>.fromJson(Map<String, dynamic> json, FromJson<T> fromJsonT)

This is the factory method that will be used to convert JSON data to a PaginatedResponse instance.

{@tool snippet}

final response = PaginatedResponse.fromJson(
 json.decode(responseBody) as Map<String, dynamic>,
User.fromJson,
);

{@end-tool}

Sample JSON response:

For Page based pagination, the response should be in the following format:

{@tool json_response_1}

{
  "data": [
    {
      "id": 1,
      "name": "John",
      "email": "[e-mail]"
    }
  ],
  "pagination|pageInfo": {
    "current_page|currentPage|page": 1,
    "per_pag|perPage": 15,
    "total|totalDocs|total_docs|count": 1
  }
}

{@end-tool}

For Cursor based pagination, the response should be in the following format: {@tool json_response_2}

{
  "data": [
    {
      "id": 1,
      "name": "John",
      "email": "[e-mail]"
    }
  ],
  "pagination|pageInfo": {
    "startCursor|start_cursor": "RandomString",
    "hasNextPage|has_next_page": false,
    "endCursor|end_cursor": "RandomString"
  }
}

{@end-tool}

Since the API response is not consistent, you can use the following snippet for page based pagination {@tool json_response_3}

{
  "data": [
    {
      "id": 1,
      "name": "John",
      "email": "[e-mail]"
    }
  ],
"current_page|currentPage|page": 1,
"per_page|perPage": 15,
"total|total_docs|totalDocs|count": 1
}

{@end-tool}

Since the API response is not consistent, you can use the following snippet for cursor based pagination {@tool json_response_4}

{
  "data": [
    {
      "id": 1,
      "name": "John",
      "email": "[e-mail]"
    }
  ],
"start_cursor|startCursor": "RandomString",
"hasNextPage|has_next_page": false,
"end_cursor|endCursor": "RandomString"
}

{@end-tool}

Implementation

factory PaginatedResponse.fromJson(
  Map<String, dynamic> json,
  FromJson<T> fromJsonT,
) {
  assert(json.containsKey('data'), 'The response must contain a data key');
  assert(json['data'] is List, 'The data must be a list');
  try {
    final response =
        List<Map<String, dynamic>>.from(json['data']).map(fromJsonT).toList();
    if (json.containsKey('pagination') || json.containsKey('pageInfo')) {
      final paginationMap =
          Map<String, dynamic>.from(json['pagination'] ?? json['pageInfo']);
      _getPaginationType(paginationMap);
      return PaginatedResponse<T>(
        data: response,
        pagination: Pagination.fromJson(paginationMap),
      );
    } else {
      _getPaginationType(json);
      return PaginatedResponse<T>(
        data: response,
        pagination: Pagination.fromJson(json),
      );
    }
  } catch (e) {
    throw Exception(e.toString());
  }
}